CMS logoCMS event Hgg
Compact Muon Solenoid
LHC, CERN

CMS-HIG-17-017 ; CERN-EP-2018-269
Search for nonresonant Higgs boson pair production in the ${\mathrm{b\bar{b}}\mathrm{b\bar{b}}}$ final state at $\sqrt{s} = $ 13 TeV
JHEP 04 (2019) 112
Abstract: Results of a search for nonresonant production of Higgs boson pairs, with each Higgs boson decaying to a $ \mathrm{b\bar{b}} $ pair, are presented. This search uses data from proton-proton collisions at a centre-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 35.9 fb$^{-1}$, collected by the CMS detector at the LHC. No signal is observed, and a 95% confidence level upper limit of 847fb is set on the cross section for standard model nonresonant Higgs boson pair production times the squared branching fraction of the Higgs boson decay to a $ \mathrm{b\bar{b}} $ pair. The same signature is studied, and upper limits are set, in the context of models of physics beyond the standard model that predict modified couplings of the Higgs boson.
Figures & Tables Summary References CMS Publications
Figures

png pdf
Figure 1:
Feynman diagrams that contribute to HH production via gluon-gluon fusion at LO. Diagrams (a) and (b) correspond to SM-like processes, while diagrams (c), (d), and (e) correspond to pure BSM effects: (c) and (d) describe contact interactions between the Higgs boson and gluons, and (e) describes the contact interaction of two Higgs bosons with top quarks.

png pdf
Figure 2:
An illustration of the hemisphere mixing procedure. The transverse thrust axis is defined as the axis on which the sum of the absolute values of the projections of the $ {p_{\mathrm {T}}} $ of the jets is maximal. Once the thrust axis is identified, the event is divided into two halves by cutting along the axis perpendicular to the transverse thrust axis. One such half is called a hemisphere (h). In a preliminary step, each event in the original $N$-event data set is split into two hemispheres that are collected in a library of $2N$ hemispheres. Once the library is created, each event is used as a basis for creating artificial events. These are constructed by picking two hemispheres from the library that are similar to the two hemispheres that make up the original event.

png pdf
Figure 3:
Comparison between the background model obtained with the hemisphere mixing technique and MC simulation of QCD multijet processes for $ {{{{p_{\mathrm {T}}}}_{\mathrm {j}}} ^{1}} $ (upper left), $ {\eta ^{1}_{\text {j}}} $ (upper right), ${{{p_{\mathrm {T}}} ^{{{\mathrm {H}} _1}}}}$ (lower left), and $ {M_{{\mathrm {H}} {\mathrm {H}}}} $ (lower right). Bias correction for the background model, described in Section 8.2, is applied by rescaling the weight of each event using the event yield ratio between corrected and uncorrected BDT distributions. Only statistical uncertainties are shown as the uncertainties related to the bias correction can not be propagated from the BDT classifier to a different variable.

png pdf
Figure 3-a:
Comparison between the background model obtained with the hemisphere mixing technique and MC simulation of QCD multijet processes for $ {{{{p_{\mathrm {T}}}}_{\mathrm {j}}} ^{1}} $. Bias correction for the background model, described in Section 8.2, is applied by rescaling the weight of each event using the event yield ratio between corrected and uncorrected BDT distributions. Only statistical uncertainties are shown as the uncertainties related to the bias correction can not be propagated from the BDT classifier to a different variable.

png pdf
Figure 3-b:
Comparison between the background model obtained with the hemisphere mixing technique and MC simulation of QCD multijet processes for $ {\eta ^{1}_{\text {j}}} $. Bias correction for the background model, described in Section 8.2, is applied by rescaling the weight of each event using the event yield ratio between corrected and uncorrected BDT distributions. Only statistical uncertainties are shown as the uncertainties related to the bias correction can not be propagated from the BDT classifier to a different variable.

png pdf
Figure 3-c:
Comparison between the background model obtained with the hemisphere mixing technique and MC simulation of QCD multijet processes for ${{{p_{\mathrm {T}}} ^{{{\mathrm {H}} _1}}}}$. Bias correction for the background model, described in Section 8.2, is applied by rescaling the weight of each event using the event yield ratio between corrected and uncorrected BDT distributions. Only statistical uncertainties are shown as the uncertainties related to the bias correction can not be propagated from the BDT classifier to a different variable.

png pdf
Figure 3-d:
Comparison between the background model obtained with the hemisphere mixing technique and MC simulation of QCD multijet processes for $ {M_{{\mathrm {H}} {\mathrm {H}}}} $. Bias correction for the background model, described in Section 8.2, is applied by rescaling the weight of each event using the event yield ratio between corrected and uncorrected BDT distributions. Only statistical uncertainties are shown as the uncertainties related to the bias correction can not be propagated from the BDT classifier to a different variable.

png pdf
Figure 4:
Comparison between the background model obtained with the hemisphere mixing technique and data in the ${m_{{\mathrm {H}}}} $ CR for the variables $ {{{{p_{\mathrm {T}}}}_{\mathrm {j}}} ^{1}} $ (upper left), $ {\eta ^{1}_{\text {j}}} $ (upper right), ${\cos {\theta ^{*}} _{{{\mathrm {H}} _1} \text {-}\mathrm {j}_1}}$ (lower left), and $CMVA_{4} $ (lower right). Bias correction for the background model, described in Section 8.2, is applied by rescaling the weight of each event using the event yield ratio between corrected and uncorrected BDT distributions in this CR. Only statistical uncertainties are shown as the uncertainties related to the bias correction can not be propagated from the BDT classifier to a different variable.

png pdf
Figure 4-a:
Comparison between the background model obtained with the hemisphere mixing technique and data in the ${m_{{\mathrm {H}}}} $ CR for the $ {{{{p_{\mathrm {T}}}}_{\mathrm {j}}} ^{1}} $ variable. Bias correction for the background model, described in Section 8.2, is applied by rescaling the weight of each event using the event yield ratio between corrected and uncorrected BDT distributions in this CR. Only statistical uncertainties are shown as the uncertainties related to the bias correction can not be propagated from the BDT classifier to a different variable.

png pdf
Figure 4-b:
Comparison between the background model obtained with the hemisphere mixing technique and data in the ${m_{{\mathrm {H}}}} $ CR for the $ {\eta ^{1}_{\text {j}}} $ variable. Bias correction for the background model, described in Section 8.2, is applied by rescaling the weight of each event using the event yield ratio between corrected and uncorrected BDT distributions in this CR. Only statistical uncertainties are shown as the uncertainties related to the bias correction can not be propagated from the BDT classifier to a different variable.

png pdf
Figure 4-c:
Comparison between the background model obtained with the hemisphere mixing technique and data in the ${m_{{\mathrm {H}}}} $ CR for the ${\cos {\theta ^{*}} _{{{\mathrm {H}} _1} \text {-}\mathrm {j}_1}}$ variable.

png pdf
Figure 4-d:
Comparison between the background model obtained with the hemisphere mixing technique and data in the ${m_{{\mathrm {H}}}} $ CR for the $CMVA_{4} $ variable. Bias correction for the background model, described in Section 8.2, is applied by rescaling the weight of each event using the event yield ratio between corrected and uncorrected BDT distributions in this CR. Only statistical uncertainties are shown as the uncertainties related to the bias correction can not be propagated from the BDT classifier to a different variable.

png pdf
Figure 5:
Comparison between the background model obtained with the hemisphere mixing technique and data in the b tag CR for the variables $ {{{{p_{\mathrm {T}}}}_{\mathrm {j}}} ^{1}} $ (upper left), $ {\eta ^{1}_{\text {j}}} $ (upper right), ${M_{{{\mathrm {H}} _1}}}$ (lower left), and ${M_{{{\mathrm {H}} _2}}}$ (lower right). Bias correction for the background model, described in Section 8.2, is applied by rescaling the weight of each event using the event yield ratio between corrected and uncorrected BDT distributions in this CR. Only statistical uncertainties are shown as the uncertainties related to the bias correction can not be propagated from the BDT classifier to a different variable.

png pdf
Figure 5-a:
Comparison between the background model obtained with the hemisphere mixing technique and data in the b tag CR for the $ {{{{p_{\mathrm {T}}}}_{\mathrm {j}}} ^{1}} $ variable. Bias correction for the background model, described in Section 8.2, is applied by rescaling the weight of each event using the event yield ratio between corrected and uncorrected BDT distributions in this CR. Only statistical uncertainties are shown as the uncertainties related to the bias correction can not be propagated from the BDT classifier to a different variable.

png pdf
Figure 5-b:
Comparison between the background model obtained with the hemisphere mixing technique and data in the b tag CR for the $ {\eta ^{1}_{\text {j}}} $ variable. Bias correction for the background model, described in Section 8.2, is applied by rescaling the weight of each event using the event yield ratio between corrected and uncorrected BDT distributions in this CR. Only statistical uncertainties are shown as the uncertainties related to the bias correction can not be propagated from the BDT classifier to a different variable.

png pdf
Figure 5-c:
Comparison between the background model obtained with the hemisphere mixing technique and data in the b tag CR for the ${M_{{{\mathrm {H}} _1}}}$ variable. Bias correction for the background model, described in Section 8.2, is applied by rescaling the weight of each event using the event yield ratio between corrected and uncorrected BDT distributions in this CR. Only statistical uncertainties are shown as the uncertainties related to the bias correction can not be propagated from the BDT classifier to a different variable.

png pdf
Figure 5-d:
Comparison between the background model obtained with the hemisphere mixing technique and data in the b tag CR for the ${M_{{{\mathrm {H}} _2}}}$ variable. Bias correction for the background model, described in Section 8.2, is applied by rescaling the weight of each event using the event yield ratio between corrected and uncorrected BDT distributions in this CR. Only statistical uncertainties are shown as the uncertainties related to the bias correction can not be propagated from the BDT classifier to a different variable.

png pdf
Figure 6:
Left: comparison of the distribution of BDT output for data (left) selected in a region of the leading versus trailing Higgs boson candidate mass plane that excludes a 60- GeV -wide box around the most probable values of the dijet masses of signal events, with the corresponding output on an artificial sample obtained from the same data set by hemisphere mixing. Right: bin-by-bin differences between data and model, in s.d. units before (upper right) and after (lower right) bias correction; pull distribution for the differences, fit to a Gaussian distribution. The bias correction uncertainty is increased to take the s.d. of the residuals to 1.0.

png pdf
Figure 7:
Results of the fit to the BDT distribution for the SM HH production signal. In the bottom panel a comparison is shown between the best fit signal and best fit background subtracted from measured data. The band, centred at zero, shows the total uncertainty.

png pdf
Figure 8:
Post-fit distribution of ${M_{{{\mathrm {H}} _1}}} $ (left) and ${M_{{{\mathrm {H}} _2}}} $ (right). Bias correction for the background model is applied by rescaling the weight of each event using the event yield ratio between corrected and uncorrected BDT distributions.

png pdf
Figure 8-a:
Post-fit distribution of ${M_{{{\mathrm {H}} _1}}} $. Bias correction for the background model is applied by rescaling the weight of each event using the event yield ratio between corrected and uncorrected BDT distributions.

png pdf
Figure 8-b:
Post-fit distribution of ${M_{{{\mathrm {H}} _2}}} $. Bias correction for the background model is applied by rescaling the weight of each event using the event yield ratio between corrected and uncorrected BDT distributions.

png pdf
Figure 9:
The observed and expected upper limits at 95% CL on the ${\sigma {({{\mathrm {p}} {\mathrm {p}} \to {{\mathrm {H}} {\mathrm {H}} \to {{\mathrm {b}} {\overline {\mathrm {b}}}} {{\mathrm {b}} {\overline {\mathrm {b}}}}}})}}$ cross section for the 13 BSM models investigated. See Table 9 for their respective parameter values.

png pdf
Figure 10:
95% CL cross section limits on ${\sigma {({{\mathrm {p}} {\mathrm {p}} \to {{\mathrm {H}} {\mathrm {H}} \to {{\mathrm {b}} {\overline {\mathrm {b}}}} {{\mathrm {b}} {\overline {\mathrm {b}}}}}})}}$ for values of ${\kappa _{{{\lambda}}}}$ in the [-20,20] range, assuming $ {\kappa _{{\mathrm {t}}}} = $ 1; the theoretical prediction with $ {\kappa _{{\mathrm {t}}}} = $ 1 is also shown.

png pdf
Figure 11:
Diagram describing the procedure used to estimate the background bias correction. All possible combinations of mixed hemispheres except those used for training are added together to create a large sample $M$ of $96N$ events from which we repeatedly subsample without replacement 200 replicas $M_i$ of $N$ events. The hemisphere mixing procedure is then carried out again for each of this replicas to produce a set of re-mixed data replicas $R_i$. The trained multivariate classifier trained is then evaluated over all the events of $M$ and each $R_i$. and the histograms of the classifier output are compared to obtain a the differences for each of the replicas. The median difference is taken as bias correction.

png pdf
Figure 12:
Bias estimation by resampling, in relative units of the statistical uncertainty of the predicted background, used to correct the background estimation. The median (red line) and the upper and lower one s.d. quantiles (green lines) have been computed from 200 subsamples of the re-mixed data comparing the predicted background $n^p_b$ with the observed $n^o_b$. The variability due to the limited number of subsamples is estimated by bootstrap and it is shown for each estimation using a coloured shadow around the quantile estimation. The light yellow shadow represents the uncertainty due to the limited statistics of the reference observed sample. The separation between the one s.d. quantiles is compatible with the expected variance if the estimation was Poisson or Gaussian distributed.
Tables

png pdf
Table 1:
The values of the anomalous coupling parameters for the 13 benchmark models studied [28]. For reference, the values of the parameters in the SM are also included.

png pdf
Table 2:
Cut-flow efficiency for the SM signal $ {{\mathrm {p}} {\mathrm {p}} \to {{\mathrm {H}} {\mathrm {H}} \to {{\mathrm {b}} {\overline {\mathrm {b}}}} {{\mathrm {b}} {\overline {\mathrm {b}}}}}} $; the efficiency and the relative reduction of each successive selection step is shown. The number of expected SM signal events for an integrated luminosity of 1 fb$^{-1}$ is also reported.

png pdf
Table 3:
List of BDT input variables.

png pdf
Table 4:
Systematic uncertainties considered in the analysis and relative impact on the expected limit for the SM HH production. The relative impact is obtained by fixing the nuisance parameters corresponding to each source and recalculating the expected limit.

png pdf
Table 5:
The observed and expected upper limits on ${\sigma {({{\mathrm {p}} {\mathrm {p}} \to {{\mathrm {H}} {\mathrm {H}} \to {{\mathrm {b}} {\overline {\mathrm {b}}}} {{\mathrm {b}} {\overline {\mathrm {b}}}}}})}}$ in the SM at 95% CL in units of fb.

png pdf
Table 6:
The observed and expected upper limits on the ${\sigma {({{\mathrm {p}} {\mathrm {p}} \to {{\mathrm {H}} {\mathrm {H}} \to {{\mathrm {b}} {\overline {\mathrm {b}}}} {{\mathrm {b}} {\overline {\mathrm {b}}}}}})}}$ cross section for the 13 BSM benchmark models at 95% CL in units of fb.
Summary
This paper presents a search for nonresonant Higgs boson pair (HH) production with both Higgs bosons decaying into $ \mathrm{b\bar{b}} $ pairs. The standard model (SM) production has been studied along with 13 beyond the SM (BSM) benchmark models, using a data set of $\sqrt{s} = $ 13 TeV proton-proton collision events, corresponding to an integrated luminosity of 35.9 fb$^{-1}$ collected by the CMS detector during the 2016 LHC run. The analysis of events acquired by a hadronic multijet trigger includes the selection of events with 4 b-tagged jets and a classification using boosted decision trees, optimized for discovery of the SM HH signal. Limits at 95% confidence level on the HH production cross section times the square of the branching fraction for the Higgs boson decay to b quark pairs are extracted for the SM and each BSM model considered, using binned likelihood fits of the shape of the boosted decision tree classifier output. The background model is derived from a novel technique based on data that provides a multidimensional representation of the dominant quantum chromodynamics multijet background and also models well the overall background distribution. The expected upper limit on ${\sigma{(\mathrm{pp\to HH \to b\bar{b}b\bar{b}})}}$ is 419 fb, corresponding to 37 times the expected value for the SM process. The observed upper limit is 847 fb. Anomalous couplings of the Higgs boson are also investigated. The upper limits extracted for the HH production cross section in the 13 BSM benchmark models range from 508 to 3513 fb.
References
1 ATLAS Collaboration Observation of a new particle in the search for the standard model Higgs boson with the ATLAS detector at the LHC PLB 716 (2012) 1 1207.7214
2 CMS Collaboration Observation of a new boson at a mass of 125 GeV with the CMS experiment at the LHC PLB 716 (2012) 30 CMS-HIG-12-028
1207.7235
3 CMS Collaboration Observation of a new boson with mass near 125 GeV in pp collisions at $ \sqrt{s} = $ 7 and 8 TeV JHEP 06 (2013) 081 CMS-HIG-12-036
1303.4571
4 ATLAS and CMS Collaborations Measurements of the Higgs boson production and decay rates and constraints on its couplings from a combined ATLAS and CMS analysis of the LHC pp collision data at $ \sqrt{s} = $ 7 and 8 TeV JHEP 08 (2016) 045 1606.02266
5 ATLAS and CMS Collaborations Combined measurement of the Higgs boson mass in pp collisions at $ \sqrt{s}= $ 7 and 8 TeV with the ATLAS and CMS experiments PRL 114 (2015) 191803 1503.07589
6 C. O. Dib, R. Rosenfeld, and A. Zerwekh Double Higgs production and quadratic divergence cancellation in little Higgs models with T parity JHEP 05 (2006) 074 hep-ph/0509179
7 R. Grober and M. Muhlleitner Composite Higgs boson pair production at the LHC JHEP 06 (2011) 020 1012.1562
8 R. Contino et al. Anomalous couplings in double Higgs production JHEP 08 (2012) 154 1205.5444
9 M. J. Dolan, C. Englert, and M. Spannowsky New physics in LHC Higgs boson pair production PRD 87 (2013) 055002 1210.8166
10 S. Dawson, A. Ismail, and I. Low What's in the loop? the anatomy of double Higgs production PRD 91 (2015) 115008 1504.05596
11 J. Baglio et al. The measurement of the Higgs self-coupling at the LHC: theoretical status JHEP 04 (2013) 151 1212.5581
12 CMS Collaboration Measurements of properties of the Higgs boson decaying into the four-lepton final state in pp collisions at $ \sqrt{s}= $ 13 TeV JHEP 11 (2017) 047 CMS-HIG-16-041
1706.09936
13 LHC Higgs Cross Section Working Group Handbook of LHC Higgs cross sections: 4. deciphering the nature of the Higgs sector CERN (2016) 1610.07922
14 D. de Florian and J. Mazzitelli Higgs boson pair production at next-to-next-to-leading order in QCD PRL 111 (2013) 201801 1309.6594
15 S. Dawson, S. Dittmaier, and M. Spira Neutral Higgs boson pair production at hadron colliders: QCD corrections PRD 58 (1998) 115012 hep-ph/9805244
16 S. Borowka et al. Higgs boson pair production in gluon fusion at next-to-leading order with full top-quark mass dependence PRL 117 (2016) 012001 1604.06447
17 D. de Florian and J. Mazzitelli Higgs pair production at next-to-next-to-leading logarithmic accuracy at the LHC JHEP 09 (2015) 053 1505.07122
18 CMS Collaboration Search for Higgs boson pair production in events with two bottom quarks and two tau leptons in proton-proton collisions at $ \sqrt{s} = $ 13 TeV PLB 778 (2018) 101 CMS-HIG-17-002
1707.02909
19 ATLAS Collaboration Search for pair production of Higgs bosons in the $ b\bar{b}b\bar{b} $ final state using proton-proton collisions at $ \sqrt{s} = $ 13 TeV with the ATLAS detector Submitted to JHEP 1804.06174
20 A. Carvalho et al. Analytical parametrization and shape classification of anomalous HH production in the EFT approach 1608.06578
21 ATLAS Collaboration Search for Higgs boson pair production in the $ b\bar{b}b\bar{b} $ final state from pp collisions at $ \sqrt{s}= $ 8 TeV with the ATLAS detector EPJC 75 (2015) 412 1506.00285
22 CMS Collaboration Search for Higgs boson pair production in the bb$\tau\tau $ final state in proton-proton collisions at $ \sqrt{s} = $ 8 TeV PRD 96 (2017) 072004 CMS-HIG-15-013
1707.00350
23 CMS Collaboration Search for resonant and nonresonant Higgs boson pair production in the $ \mathrm{b\bar{b}}\ell\nu\ell\nu $ final state in proton-proton collisions at $ \sqrt{s} = $ 13 TeV JHEP 01 (2018) 054 CMS-HIG-17-006
1708.04188
24 CMS Collaboration Search for Higgs boson pair production in the $ \gamma\gamma\mathrm{b\bar{b}} $ final state in pp collisions at $ \sqrt{s} = $ 13 TeV Submitted to PLB CMS-HIG-17-008
1806.00408
25 CMS Collaboration Search for production of Higgs boson pairs in the four b quark final state using large-area jets in proton-proton collisions at $ \sqrt{s}= $ 13 TeV Submitted to JHEP CMS-B2G-17-019
1808.01473
26 A. Falkowski Effective field theory approach to LHC Higgs data Pramana 87 (2016) 39 1505.00046
27 T. Corbett et al. The Higgs legacy of the LHC run I JHEP 08 (2015) 156 1505.05516
28 A. Carvalho et al. Higgs pair production: Choosing benchmarks with cluster analysis JHEP 04 (2016) 126 1507.02245
29 CMS Collaboration The CMS trigger system JINST 12 (2017) P01020 CMS-TRG-12-001
1609.02366
30 CMS Collaboration The CMS experiment at the CERN LHC JINST 3 (2008) S08004 CMS-00-001
31 CMS Collaboration Identification of heavy-flavour jets with the CMS detector in pp collisions at 13 TeV JINST 13 (2018) P05011 CMS-BTV-16-002
1712.07158
32 B. Hespel, D. L\'opez-Val, and E. Vryonidou Higgs pair production via gluon fusion in the two-Higgs-doublet model JHEP 09 (2014) 124 1407.0281
33 J. Alwall et al. The automated computation of tree-level and next-to-leading order differential cross sections, and their matching to parton shower simulations JHEP 07 (2014) 079 1405.0301
34 NNPDF Collaboration Parton distributions for the LHC Run II JHEP 04 (2015) 040 1410.8849
35 A. Carvalho et al. On the reinterpretation of non-resonant searches for Higgs boson pairs 1710.08261
36 T. Sjostrand et al. An introduction to PYTHIA 8.2 CPC 191 (2015) 159 1410.3012
37 J. Alwall et al. Comparative study of various algorithms for the merging of parton showers and matrix elements in hadronic collisions EPJC 53 (2008) 473 0706.2569
38 P. Nason A new method for combining NLO QCD with shower Monte Carlo algorithms JHEP 11 (2004) 040 hep-ph/0409146
39 S. Frixione, P. Nason, and C. Oleari Matching NLO QCD computations with parton shower simulations: the POWHEG method JHEP 11 (2007) 070 0709.2092
40 S. Alioli, P. Nason, C. Oleari, and E. Re A general framework for implementing NLO calculations in shower Monte Carlo programs: the POWHEG BOX JHEP 06 (2010) 043 1002.2581
41 J. M. Campbell, R. K. Ellis, P. Nason, and E. Re Top-pair production and decay at NLO matched with parton showers JHEP 04 (2015) 114 1412.1828
42 S. Alioli, P. Nason, C. Oleari, and E. Re NLO single-top production matched with shower in POWHEG: $ s $- and $ t $-channel contributions JHEP 09 (2009) 111 0907.4076
43 H. B. Hartanto, B. Jager, L. Reina, and D. Wackeroth Higgs boson production in association with top quarks in the POWHEG BOX PRD 91 (2015) 094003 1501.04498
44 E. Bagnaschi, G. Degrassi, P. Slavich, and A. Vicini Higgs production via gluon fusion in the POWHEG approach in the SM and in the MSSM JHEP 02 (2012) 088 1111.2854
45 G. Luisoni, P. Nason, C. Oleari, and F. Tramontano $ {\text{HW}^\pm}/\text{HZ} + 0 $ and 1 jet at NLO with the POWHEG BOX interfaced to GoSam and their merging within MiNLO JHEP 10 (2013) 083 1306.2542
46 CMS Collaboration Investigations of the impact of the parton shower tuning in Pythia 8 in the modelling of $ \mathrm{t\overline{t}} $ at $ \sqrt{s}= $ 8 and 13 TeV CMS-PAS-TOP-16-021 CMS-PAS-TOP-16-021
47 CMS Collaboration Event generator tunes obtained from underlying event and multiparton scattering measurements EPJC 76 (2016) 155 CMS-GEN-14-001
1512.00815
48 A. Buckley et al. LHAPDF6: parton density access in the LHC precision era EPJC 75 (2015) 132 1412.7420
49 GEANT4 Collaboration GEANT4--a simulation toolkit NIMA 506 (2003) 250
50 CMS Collaboration Particle-flow reconstruction and global event description with the CMS detector JINST 12 (2017) P10003 CMS-PRF-14-001
1706.04965
51 M. Cacciari, G. P. Salam, and G. Soyez The anti-$ {k_{\mathrm{T}}} $ jet clustering algorithm JHEP 04 (2008) 063 0802.1189
52 M. Cacciari, G. P. Salam, and G. Soyez FastJet user manual EPJC 72 (2012) 1896 1111.6097
53 CMS Collaboration Jet energy scale and resolution in the CMS experiment in pp collisions at 8 TeV JINST 12 (2017) P02014 CMS-JME-13-004
1607.03663
54 CMS Collaboration Pileup jet identification CMS-PAS-JME-13-005 CMS-PAS-JME-13-005
55 T. Chen and C. Guestrin XGBoost: A scalable tree boosting system in Proceedings of the 22nd ACM SIGKDD International Conference on Knowledge Discovery and Data Mining, KDD '16 ACM, New York, NY, USA
56 P. De Castro Manzano et al. Hemisphere mixing: a fully data-driven model of QCD multijet backgrounds for LHC searches in Proceedings, 2017 European Physical Society Conference on High Energy Physics (EPS-HEP 2017), volume EPS-HEP2017, p. 370 2017 1712.02538
57 CMS Collaboration Measurement of the inelastic proton-proton cross section at $ \sqrt{s}= $ 13 TeV Submitted to JHEP CMS-FSQ-15-005
1802.02613
58 CMS Collaboration CMS luminosity measurements or the 2016 data taking period CMS-PAS-LUM-17-001 CMS-PAS-LUM-17-001
59 J. Butterworth et al. PDF4LHC recommendations for LHC Run II JPG 43 (2016) 023001 1510.03865
60 G. Cowan, K. Cranmer, E. Gross, and O. Vitells Asymptotic formulae for likelihood-based tests of new physics EPJC 71 (2011) 1554 1007.1727
61 A. L. Read Presentation of search results: The CLs technique JPG 28 (2002)
62 T. Junk Confidence level computation for combining searches with small statistics NIMA 434 (1999) 435 hep-ex/9902006
63 The ATLAS Collaboration, The CMS Collaboration, The LHC Higgs Combination Group Procedure for the LHC Higgs boson search combination in Summer 2011 CMS-NOTE-2011-005
Compact Muon Solenoid
LHC, CERN